I read about the story of moses in the quran. It is mentioned a number of times including the conversation that Allah had with moses. However, although in essence the words in the conversation meant the same,there are variations amongst the verses in this. I was wondering what is the reason for this?There must be some reason for this variations,hope someone could clarify this for me.The verses are reproduced below:

28:30

But when he came close to it, he was called from the right side of the valley in the blessed field, from the tree, “O Moses! Behold! I, certainly I am God, the Lord of the Worlds.”

27:9

“O Moses! It is I, God, the Almighty, the Wise.”

20:14

Surely, I, I alone am God, there is no god but Me. Therefore, serve Me alone, and establish the Divine Order in the land for My remembrance.

Thank you for your time brothers and sisters._________________Inna lillahi,wa inna ilayhi ra'jiun
To God we belong,To Him is the return!